What are the pressures acting on a submarine at a depth of 50 m to the pressures at a depth of 200 m?

Answer 1

Atmospheric pressure is approximately 14.7 psi at sea level, and it is increased by 14.7 psi every 33' (10.0584 m), or 2 atmospheres (29.4 PSIA, or lbs/square inch absolute). Since we know that at 33' the pressure exerted is 14.7 lbs/square inch, the PSI per foot of sea water value is .445 psi (14.7 divided by 33), e.g., a 33' column of sea water 1" wide would weigh 14.7lbs.

It's always easier to figure the depth calculation per foot of sea water pressure and then add the figure for atmospheric pressure to get PSIA. 50m equates to 164.5 feet, so at 50m the pressure would be 164.5 x .445, or 73.2 psi. Accounting for atmospheric pressure, we add 14.7 to 73.2 and get a total of 87.9 PSIA on the hull.

200m equates to 656.167 feet, which is 291.994 psi. To get the total absolute pressure on the hull at 200m we add 14.7 to 291.994, and arrive at a total of 306.69 PSIA.

The figure changes for fresh water - it takes 34' of fresh water to equal 2 atmospheres.